| Manatsu no Kōsen | |
| Cover: | Manatsu.jpg |
| Type: | single |
| Artist: | Morning Musume |
| Album: | Second Morning |
| Released: | May 12, 1999 (JP) |
| Recorded: | 1999 |
| Genre: | Japanese Pop |
| Length: | 14:33 (8 cm CD) 19:42 (12 cm CD) |
| Label: | zetima |
| Producer: | Tsunku |
| Prev Title: | Memory Seishun no Hikari |
| Prev Year: | 1999 |
| Next Title: | Furusato |
| Next Year: | 1999 |
is the fifth single of the J-pop idol group Morning Musume, released on May 12, 1999, as an 8 cm CD. It sold a total of 235,010 copies, and reached number three on the Oricon Charts. In 2004, it was re-released as part of the Early Single Box and again in 2005, as a 12 cm CD. The lead vocalist of this single was Natsumi Abe. It was first single without Asuka Fukuda.